The invention relates to an apparatus and method for separating solid particles from a liquid. An example of a use for the apparatus and method of this invention is during the production of coke from coal, such as in by-product coke ovens. In this example, the invention is used for the separation of fine coal particles and agglomerates from flushing liquor from a charging main on a coke oven battery.
There are many situations, especially in industry, where solid particles need to be removed from a liquid. These situations include removal of comparatively light particles which tend to float at or close to the surface of the liquid and removal of comparatively heavy particles which tend to sink to the bottom of a liquid in an enclosure. Prior art clarifiers and classifiers are disclosed in Chemical Engineer's Handbook, edited by Perry, Chilton and Kirkpatrick, published by McGraw Hill Book Co., Inc., New York, 1963, page 21-52 to page 21-63. In by-product coke ovens the use of a flushing liquor to treat gases in a charging main is a comparatively new development in coke oven operation and should be distinguished from the use of a flushing liquor to treat gases in a collecting main. Treatment of gases in a charging main is performed to remove fine coal particles and agglomerates which are carried over with the gases emanating during the charging operation prior to coking and the very early stages during the coking cycle, e.g. 1-2 hours. Treatment of by-product gases in a collecting main is performed to remove tar and other by-product constituents during essentially the entire coking operation. The treatment of gases in a collecting main and treatment of flushing liquor from the collecting main is described in "Coal, Coke and Coal Chemicals" by Philip J. Wilson, Jr. and Joseph H. Wells, published by McGraw-Hill Book Company, Inc., 1950, pages 240-245. Prior art methods and apparatus for the treatment of the flushing liquor from the collector main include flowing the flushing liquor into a decanter, over a fixed weir, then to a collector tank, as described in "Coal, Coke and Coal Chemicals", pages 244-245. Such a decanter operates to remove tar after coking, rather than removing fine coal particles and agglomerates before coking. U.S. Pat. No. 3,804,721 to W. F. Gidick briefly refers to treating dirty liquor to remove coal particles.